The incidence of otoneurologic symptoms and signs is high among individuals sustaining trauma to the head in industrial and traffic accidents. The type of otoneurologic manifestations and the time of their onset are variable according to the nature of head trauma. The aim of this study was to correlate experimentally induced blunt head trauma with their associated histopathologic findings in guinea pigs. In order to make an animal model similar to human cases, the method of holding the animal's tail was chosen to simulate the conditions of humans whose heads are freely movable at the time of impact. 12 guinea pigs were used. ABRs were taken pre-and post-head trauma and 8 of 12 experimental animals showed abnormal wave patterns. Those animals were sacrificed 7 days following head trauma and temporal bones were processed for light microscopic examination. The results were as follows : 1) There were no fractures of the osseous labyrinths and no dislocations of the ossicles. 2) Extravasation of red blood cells was found mostly in the scala tympani in 8 cases. 3) There was degeneration of the organ of Corti, and hemorrhage in and laceration of the eighth nerve in 8 animals. 4) Eight animals also showed an accumulation of cloud substance(nubacula) in the vestibular and tympani scalae. 5) Detachment or destrucitve changes of the stria vascularis were found in 2 animals and atrophic change of the spiral ganglion cell was found in 1 animal. Four of 12 animals, however, showed no changes at the ABRs. These 4 animals also showed none of the pathologic findings which appeared in 8 animals. According to the above results, these factors may play a role in the development of progressive sensorineural hearing loss.